SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15bed40f8fadc21286fe32ad45890225649a5f4ff442318b017f1144fcc3934a' 
  AND token = 'zxW+85NNuZWYJKFXJjBWwuHZHySSap4o44gjZzGhmEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}